French viscerotropic yellow fever virus will be transmitted from rhesus monkeys by Aedes aegypti from Thailand, Santo Domingo, and East Africa to assess relative vector competence. In artificial feeding experiments parallel studies will be done with PR 156 dengue 2 virus from the Caribbean. A new Japanese hamster cell line will be assayed as a tool for the neutralization test with rabies serogroup viruses. Hemagglutinating antigens for vesicular stomatitis group and rabies serogroup viruses will be prepared and cross compared serologically in the HI test. Kinetic HI and neutralization tests will be attempted with a variety of CHF-Congo virus strains to try to determine geographic variation.